What is the purpose of phosphorus removal structures in edge-of-field practices?

• A. To add phosphorus to water bodies.
• B. To filter out phosphorus from runoff before it enters water bodies.
• C. To reduce soil pH.
• D. To remove nitrogen from runoff.

Answer: (B)

Phosphorus removal structures are used at the edge of fields to keep phosphorus out of water bodies by filtering and trapping it as runoff passes through the structure. Phosphorus tends to bond to soil particles, so these structures capture sediment-bound phosphorus and other particulate matter, allowing cleaner water to flow into streams or lakes. This reduces the phosphorus load that drives algal blooms and eutrophication in receiving waters.

They aren’t meant to add phosphorus to water, nor to change soil pH, and removing phosphorus is distinct from removing nitrogen, which involves different processes.